Activity

[I’ll also talk a bit about frostbite below]

Pneumonia is a significant possibility due to aspirated water – that is, if he inhaled any water during the initial splash, or if he was under water long enough that he involuntarily gasped for air and inhaled water instead. Natural water isn’t purified and there isn’t really any telling what microorganisms might be living in it. River water is generally purer than stagnant pond or marsh water, and lake water may either be clean(er) if it drains into another river or into some kind of aquifer / water system. Cold water is not necessarily purer than warmer water; although warm / tropical water is host to a great many parasites and bugs, and most bacteria generally thrive in warm water rather than frozen water, a number of dangerous bacteria produce endospores through which they can hibernate through severe temperature extremes, some even up to boiling (though not forever).

Furthermore, the shock of hypothermia sabotages the body’s normal immune response. There’s already a significant risk of pneumonia with regular near-drowning, but if the victim can’t get warm and restore normal circulation and organ function, then their risk of developing a more severe infection increases significantly.

A brief primer on what constitutes pneumonia – it’s an infection of the lungs, whether viral, bacterial, fungal, or protazoal in nature. This infection causes inflammation and fluid accumulation on the inner surface of the lung’s alveoli, obstructing the exchange of oxygen and carbon dioxide between blood and air, making it harder to breathe and breathing less effective. Pneumonia is often accompanied by a productive cough, though usually not a bloody cough; a bloody cough may indicate a severe infection, or even tuberculosis

There did in fact exist a substantial number of medieval medicines for various infections, including pneumonia, and they didn’t all involve leeches, and while their inventors didn’t know of microorganisms, they did test their cocktails quite rigorously (ethical restrictions being not quite what it is today) to ensure their effectiveness. A modern experiment tested one recipe called Bald’s eyesalve, which contains wine, garlic, an Allium species (such as leek or onion) and oxgall (bile from an ox). The recipe stated that, after the ingredients have been mixed together, they must stand in a brass vessel for nine nights before use. This recipe was found to be effective on Methicillin-Resistant-Staph-Aureus, an antibiotic resistant bacteria strain found commonly in hospitals and long-term care facilities. The second, greater challenge would be application, as this is a medicine for an eye infection or any other surface wound; this would not be effective in the lungs. I would have to do more research to give you a better answer, but it is plausible that there were also recipes designed to be boiled into vapor and inhaled, though the apparatus necessary to make a medieval nebulizer would be complex indeed and well beyond the reach of a frontier healer in a frozen wilderness, or indeed any doctor outside of a major city with its own medical establishment.

As mentioned previously, pneumonia causes fluid accumulation in and around the affected lung. This may be directly treated by puncturing the thoracic cavity with a pipe, carefully avoiding puncturing the lung or heart; this creates a negative pressure outlet which will gradually suction out accumulated fluid or air. This operation carries a high risk of additional infection, but may be required emergently if the patient is unable to breathe.

Otherwise, treatment for pneumonia is primarily going to be supportive, secondary to the hypothermia; keep the patient well fed and warm, keep them sitting upright to encourage fluid to drain away from the upper lobes which improves gas exchange, and wait for the patient’s immune system to fight off the infection.

Now, Frostbite:

Frostbite essentially consists of the literal freezing of your tissues, together with their blood vessels. The expansion of water as it turns to ice destroys cells while metabolic processes slow or cease entirely. Circulation stops to frozen body parts, and if not treated quickly, frostbite can result in tissue death and going necrotic – that is, rotting on the body. This can quickly become gangrene and turn into sepsis if it is not amputated in a timely manner. The severity of the frostbite is going to depend on the temperature, wind chill, if the victim was also wet at the time, and duration of exposure to extreme cold, as well as his treatment. The treatment for frostbite is similar to the process for treating hypothermia; warm the affected extremities as quickly as possible without scalding them; this is critically important, as frozen tissue is numb, and the victim won’t be able to tell if the frostbitten extremities are burning until most of the damage is already done, as the nerves which would conduct the pain sensation to the brain are deep inside your flesh, not on the surface where the boiling water is scalding your poor hand meat. For the same reason, massaging the affected areas is discouraged, as it will do little to restore circulation or warmth and is more likely to break off frozen skin and flesh – much like frozen chicken tenders. :)))
A healer might know this and avoid massage and/or restrain their patient from doing it themselves, but your average medieval joe / jane probably won’t.